1. Field of the invention
The present invention relates to a packaged solid electrolytic capacitor of the type which comprises a capacitor element made of a valve metal such as tantalum, niobium or aluminum, and a synthetic resin package enclosing the capacitor element. The present invention also relates to a method of making such a capacitor.
2. Description of the Related Art
A conventional method for collectively producing a plurality of packaged solid electrolytic capacitors may utilize a metal lead frame as shown in FIG. 154 of the accompanying drawings. Specifically, the illustrated lead frame A is elongated in one direction and includes a number of pairs of right and left lead portions B and C. The respective pairs of the lead portions B and C are arranged at regular intervals longitudinally of the lead frame A. As shown, a capacitor element D is mounted on each pair of the right and left lead portions B, C.
Each capacitor element D is provided with an anode D1 and a cathode D2 which are connected to the right lead portion B and the left lead portion C, respectively. After being thus mounted, the capacitor element D as a whole is enclosed by a protection package E made of a thermosetting resin. Then, the packaged capacitor element D is cut off the lead frame A, with the paired lead portions B and C remaining to protrude from the package E. Finally, as shown in FIG. 155, the protruding lead portions B and C are downwardly bent and further toward the bottom surface of the package E.
According to the conventional method, the respective packages E are made separately from each other by e.g. transfer molding of a synthetic resin. In this manner, disadvantageously, each package E tends to be rather bulky to compensate for inaccurate mounting of the capacitor element D. Specifically, as indicated by broken lines in FIGS. 155 and 156, the capacitor element D to be mounted on the lead portions B and C may positionally deviate vertically (FIG. 155) and/or horizontally (FIG. 156). To deal with such positional deviation, it is necessary to cause the vertical dimensions H1xe2x80x2 and H2xe2x80x2 of the package E (FIG. 155) and the horizontal dimension W1xe2x80x2 (FIG. 156) to be unduly large. Accordingly, the overall height Hxe2x80x2 and width Wxe2x80x2 of the conventional capacitor need to be increased. This means that the volumetric efficiency or ratio of the capacitor element to the entirety of the capacitor is degraded. Disadvantageously, the conventional capacitor is unduly large for the capacitance of the capacitor element.
Further, the conventional capacitor is provided with two protruding leads B, C bent toward the bottom surface of the package E to be surface-mounted onto e.g. a printed circuit board. With such leads B and C provided, the overall weight and length L of the conventional capacitor are unnecessarily increased, and the production cost becomes unduly large.
It is, therefore, an object of the present invention to provide a solid electrolytic capacitor designed to overcome the above problems.
Another object of the present invention is to provide a method of making such capacitors collectively.
According to a first aspect of the present invention, there is provided a solid electrolytic capacitor comprising: a capacitor element having an anode and a cathode; a base sheet member having an obverse surface for mounting the capacitor element and a reverse surface opposite to the obverse surface; a protection package formed on the obverse surface of the sheet member to enclose the capacitor element, the package having a first side surface adjacent to the anode of the capacitor element and a second side surface opposite to the first side surface; a conductive outer anode layer electrically connected to the anode of the capacitor element; and a conductive outer cathode layer electrically connected to the cathode of the capacitor element. The outer anode layer is formed on at least either one of the package and the sheet member. Likewise, the outer cathode layer is formed on at least either one of the package and the sheet member.
With the above arrangement, the overall height of the capacitor is rendered smaller than that of the conventional capacitor, since the capacitor element is supported by the base sheet member. Further, since the capacitor element is mounted on the sheet member, the positional deviation of the capacitor element is advantageously reduced.
According to a preferred embodiment, the solid electrolytic capacitor may further comprise an upper sheet member for shielding the capacitor element. In this case, the capacitor element may be arranged between the base sheet member and the upper sheet member.
Preferably, the package may be formed with an at least partially slanted portion so that the polarities of the anode layer and the cathode layer are readily discerned.
Preferably, the outer anode layer may be formed on at least either one of the first side surface of the package and the reverse surface of the base sheet member. Likewise, the outer cathode layer may be formed on at least either one of the second side surface of the package and the reverse surface of the base sheet member.
According to a preferred embodiment, the anode may be exposed at the first side surface of the package to come into contact with the outer anode layer.
According to another preferred embodiment, the solid electrolytic capacitor may further comprise a metal piece attached to the anode of the capacitor element. The metal piece may be exposed at the first side surface of the package to come into contact with the outer anode layer.
According to another preferred embodiment, the solid electrolytic capacitor may comprise both a metal piece attached to the anode of the capacitor element and an anode connection layer formed on the obverse surface of the base sheet member. The anode connection layer may be connected to the metal piece and exposed at the first side surface of the package to come into contact with the outer anode layer.
According to another preferred embodiment, the base sheet member may be formed with a through-hole for connecting the anode connection layer to the outer anode layer.
According to another preferred embodiment, the solid electrolytic capacitor may further comprise a cathode connection layer formed on the obverse surface of the base sheet member and connected to the cathode of the capacitor element. The cathode connection layer may be exposed at the second side surface of the package to come into contact with the outer cathode layer.
Preferably, the solid electrolytic capacitor may comprise a cathode bump arranged on the cathode of the capacitor element. The cathode bump may be exposed at the second side surface of the package to come into contact with the outer cathode layer.
According to a preferred embodiment, the solid electrolytic capacitor may comprise a cathode connection layer formed on the obverse surface of the base sheet member and connected to the cathode of the capacitor element. The base sheet member may be formed with a through-hole for connecting the cathode connection layer to the outer cathode layer.
According to a second aspect of the present invention, there is provided a method of making a solid electrolytic capacitor comprising the steps of: preparing a sheet member having an obverse surface and a reverse surface, the obverse surface being provided with at least one cathode connection layer; placing a capacitor element having an anode and a cathode onto the obverse surface of the sheet member so that the cathode of the capacitor element comes into contact with the cathode connection layer; forming a resin plate on the obverse surface of the sheet member to enclose the capacitor element; cutting the resin plate to generate a first cut surface and a second cut surface, the anode of the capacitor element being exposed at the first cut surface, the cathode connection layer being exposed at the second cut surface; forming an anode terminal layer on the first cut surface; forming a cathode terminal layer on the second cut surface; and cutting the resin plate to provide a product capacitor.
Preferably, at least either one of the first and the second cut surfaces may include an at least partially slanted portion.
According to a third aspect of the present invention, there is provided a method of making a solid electrolytic capacitor comprising the steps of: preparing a sheet member having an obverse surface and a reverse surface, the obverse surface being provided with at least one cathode connection layer, the reverse surface being provided with at least one cathode electrode layer, the sheet member being formed with a through-hole for electrically connecting the cathode connection layer to the cathode electrode layer; placing a capacitor element having an anode and a cathode onto the obverse surface of the sheet member so that the cathode of the capacitor element comes into contact with the cathode connection layer; forming a resin plate on the obverse surface of the sheet member to enclose the capacitor element; cutting the resin plate to generate a first cut surface and a second cut surface, the anode of the capacitor element being exposed at the first cut surface; forming an anode terminal layer on the first cut surface; and cutting the resin plate to provide a product capacitor.
According to a fourth aspect of the present invention, there is provided a method of making a solid electrolytic capacitor comprising the steps of: preparing a sheet member having an obverse surface and a reverse surface, the obverse surface being provided with at least one cathode connection layer; preparing at least one capacitor element having an anode and a cathode; attaching a metal piece to the anode of the capacitor element; placing the capacitor element onto the obverse surface of the sheet member so that the cathode of the capacitor element comes into contact with the cathode connection layer; forming a resin plate on the obverse surface of the sheet member to enclose the capacitor element; cutting the resin plate to generate a first cut surface and a second cut surface, the metal piece of the capacitor element being exposed at the first cut surface, the cathode connection layer being exposed at the second cut surface; forming an anode terminal layer on the first cut surface; forming a cathode terminal layer on the second cut surface; and cutting the resin plate to provide a product capacitor.
According to a fifth aspect of the present invention, there is provided a method of making a solid electrolytic capacitor comprising the steps of: preparing a sheet member having an obverse surface and a reverse surface, the obverse surface being provided with at least one cathode connection layer, the reverse surface being provided with at least one cathode electrode layer, the sheet member being formed with an through-hole for electrically connecting the cathode connection layer to the cathode electrode layer; preparing a capacitor element having an anode and a cathode; attaching a metal piece to the anode of the capacitor element; placing the capacitor element onto the obverse surface of the sheet member so that the cathode of the capacitor element comes into contact with the cathode connection layer; forming a resin plate on the obverse surface of the sheet member to enclose the capacitor element; cutting the resin plate to generate a first cut surface and a second cut surface, the metal piece of the capacitor element being exposed at the first cut surface; forming an anode terminal layer on the first cut surface; and cutting the resin plate to provide a product capacitor.
According to a sixth aspect of the present invention, there is provided a method of making a solid electrolytic capacitor comprising the steps of: preparing a capacitor element having an anode, a cathode and a cathode bump formed on the cathode; placing the capacitor element onto a sheet member; forming a resin plate on the sheet member to enclose the capacitor element; cutting the resin plate to generate a first cut surface and a second cut surface, the anode of the capacitor element being exposed at the first cut surface, the cathode bump being exposed at the second cut surface; forming an anode terminal layer on the first cut surface; forming a cathode terminal layer on the second cut surface; and cutting the resin plate to provide a product capacitor.
According to a seventh aspect of the present invention, there is provided a method of making a solid electrolytic capacitor comprising the steps of: preparing a capacitor element provided with a cathode, a cathode bump formed on the cathode, an anode, and a metal piece attached to the anode; placing the capacitor element onto a sheet member; forming a resin plate on the sheet member to enclose the capacitor element; cutting the resin plate to generate a first cut surface and a second cut surface, the metal piece of the capacitor element being exposed at the first cut surface, the cathode bump being exposed at the second cut surface; forming an anode terminal layer on the first cut surface; forming a cathode terminal layer on the second cut surface; and cutting the resin plate to provide a product capacitor.
According to an eighth aspect of the present invention, there is provided a method of making a solid electrolytic capacitor comprising the steps of: preparing a lower sheet member having an obverse surface and a reverse surface, the obverse surface being provided with at least one cathode connection layer; placing a capacitor element having an anode and a cathode onto the obverse surface of the lower sheet member so that the cathode of the capacitor element comes into contact with the cathode connection layer; stacking an upper sheet member on the capacitor element; supplying a resin material into a space between the lower and the upper sheet members to enclose the capacitor element; hardening the supplied resin material to form a resin plate attached to the lower and the upper sheet members, the resin plate and the lower and the upper sheet members constituting a plate assembly; cutting the plate assembly to generate a first cut surface and a second cut surface, the anode of the capacitor element being exposed at the first cut surface, the cathode connection layer being exposed at the second cut surface; forming an anode terminal layer on the first cut surface; forming a cathode terminal layer on the second cut surface; and cutting the plate assembly to provide a product capacitor.
According to a ninth aspect of the present invention, there is provided a method of making a solid electrolytic capacitor comprising the steps of: preparing a lower sheet member having an obverse surface and a reverse surface, the obverse surface being provided with at least one cathode connection layer, the reverse surface being provided with at least one cathode electrode layer, the lower sheet member being formed with a through-hole for electrically connecting the cathode connection layer to the cathode electrode layer;
placing a capacitor element having an anode and a cathode onto the obverse surface of the sheet member so that the cathode of the capacitor element comes into contact with the cathode connection layer; stacking an upper sheet member on the capacitor element; supplying a resin material into a space between the lower and the upper sheet members to enclose the capacitor element; hardening the supplied resin material to form a resin plate attached to the lower and the upper sheet members, the resin plate and the lower and the upper sheet members constituting a plate assembly; cutting the plate assembly to generate a first cut surface and a second cut surface, the anode of the capacitor element being exposed at the first cut surface; forming an anode terminal layer on the first cut surface; and cutting the plate assembly to provide a product capacitor.
According to a tenth aspect of the present invention, there is provided a method of making a solid electrolytic capacitor comprising the steps of: preparing a lower sheet member having an obverse surface and a reverse surface, the obverse surface being provided with at least one cathode connection layer; preparing a capacitor element having a cathode, an anode, and a metal piece attached to the anode; placing the capacitor element onto the obverse surface of the lower sheet member so that the cathode of the capacitor element comes into contact with the cathode connection layer; stacking an upper sheet member on the capacitor element; supplying a resin material into a space between the lower and the upper sheet members to enclose the capacitor element; hardening the supplied resin material to form a resin plate attached to the lower and the upper sheet members, the resin plate and the lower and the upper sheet members constituting a plate assembly; cutting the plate assembly to generate a first cut surface and a second cut surface, the metal piece of the capacitor element being exposed at the first cut surface, the cathode connection layer being exposed at the second cut surface; forming an anode terminal layer on the first cut surface; forming a cathode terminal layer on the second cut surface; and cutting the plate assembly to provide a product capacitor.
According to an eleventh aspect of the present invention, there is provided a method of making a solid electrolytic capacitor comprising the steps of: preparing a capacitor element having an anode, a cathode and a cathode bump formed on the cathode; placing the capacitor element onto a lower sheet member; stacking an upper sheet member on the capacitor element; supplying a resin material into a space between the lower and the upper sheet members to enclose the capacitor element; hardening the supplied resin material to form a resin plate attached to the lower and the upper sheet members, the resin plate and the lower and the upper sheet members constituting a plate assembly; cutting the plate assembly to generate a, first cut surface and a second cut surface, the anode of the capacitor element being exposed at the first cut surface, the cathode bump being exposed at the second cut surface; forming an anode terminal layer on the first cut surface; forming a cathode terminal layer on the second cut surface; and cutting plate assembly to provide a product capacitor.
According to a twelfth aspect of the present invention, there is provided a method of making a solid electrolytic capacitor element comprising the steps of: preparing a capacitor element provided with a cathode, a cathode bump formed on the cathode, an anode, and a metal piece attached to the anode; placing the capacitor element onto a lower sheet member; stacking an upper sheet member on the capacitor element; supplying a resin material into a space between the lower and the upper sheet members to enclose the capacitor element; hardening the supplied resin material to form a resin plate attached to the lower and the upper sheet members, the resin plate and the lower and the upper sheet members constituting a plate assembly; cutting the plate assembly to generate a first cut surface and a second cut surface, the metal piece of the capacitor element being exposed at the first cut surface, the cathode bump being exposed at the second cut surface; forming an anode terminal layer on the first cut surface; forming a cathode terminal layer on the second cut surface; and cutting the plate assembly to provide a product capacitor.
According to a thirteenth aspect of the present invention, there is provided a method of making a solid electrolytic capacitor comprising the steps of: preparing a sheet member having an obverse surface and a reverse surface, the obverse surface being formed with at lease one pair of an anode connection layer and a cathode connection layer, the reverse surface being formed with at least one pair of an anode electrode layer and a cathode electrode layer, the sheet member being formed with a first through-hole for electrically connecting the anode connection layer to the anode electrode layer and with a second through-hole for electrically connecting the cathode connection layer to the cathode electrode layer; placing a capacitor element having an anode and a cathode onto the obverse surface of the sheet member so that the cathode of the capacitor element comes into contact with the cathode connection layer; forming a resin plate on the obverse surface of the sheet member to enclose the capacitor element; and cutting the resin plate to provide a product capacitor.
According to a fourteenth aspect of the present invention, there is provided a method of making a solid electrolytic capacitor comprising the steps of: preparing a sheet member having an obverse surface and a reverse surface, the obverse surface being formed with at lease one pair of an anode connection layer and a cathode connection layer, the reverse surface being formed with at least one pair of an anode electrode layer and a cathode electrode layer, the sheet member being formed with a first through-hole for electrically connecting the anode connection layer to the anode electrode layer and with a second through-hole for electrically connecting the cathode connection layer to the cathode electrode layer; preparing a capacitor element having an anode, a cathode and a metal piece attached to the anode; placing the capacitor element onto the sheet member so that the metal piece comes into contact with the anode connection layer and that the cathode comes into contact with the cathode connection layer; forming a resin plate on the sheet member to enclose the capacitor element; and cutting the resin plate to provide a product capacitor.
According to a fifteenth aspect of the present invention, there is provided a method of making a solid electrolytic capacitor comprising the steps of: preparing a lower sheet member having an obverse surface and a reverse surface, the obverse surface being formed with at lease one pair of an anode connection layer and a cathode connection layer, the reverse surface being formed with at least one pair of an anode electrode layer and a cathode electrode layer, the lower sheet member being formed with a first through-hole for electrically connecting the anode connection layer to the anode electrode layer and with a second through-hole for electrically connecting the cathode connection layer to the cathode electrode layer; placing a capacitor element having an anode and a cathode onto the lower sheet member so that the anode comes into contact with the anode connection layer and that the cathode comes into contact with the cathode connection layer; stacking an upper sheet member on the capacitor element; supplying a resin material into a space between the lower and the upper sheet members to enclose the capacitor element; hardening the supplied resin material to form a resin plate attached to the lower and the upper sheet members, the resin plate and the lower and the upper sheet members constituting a plate assembly; and cutting the plate assembly to provide a product capacitor.
According to a sixteenth aspect of the present invention, there is provided a method of making a solid electrolytic capacitor comprising the steps of: preparing a lower sheet member having an obverse surface and a reverse surface, the obverse surface being formed with at lease one pair of an anode connection layer and a cathode connection layer, the reverse surface being formed with at least one pair of an anode electrode layer and a cathode electrode layer, the lower sheet member being formed with a first through-hole for electrically connecting the anode connection layer to the anode electrode layer and with a second through-hole for electrically connecting the cathode connection layer to the cathode electrode layer; preparing a capacitor element having an anode, a cathode and a metal piece attached to the anode; placing the capacitor element onto the lower sheet member so that the metal piece comes into contact with the anode connection layer and that the cathode comes into contact with the cathode connection layer; stacking an upper sheet member on the capacitor element; supplying a resin material into a space between the lower and the upper sheet members to enclose the capacitor element; hardening the supplied resin material to form a resin plate attached to the lower and the upper sheet members, the resin plate and the lower and the upper sheet members constituting a plate assembly; and cutting the plate assembly to provide a product capacitor.
Other features and advantages of the present invention will become apparent from the detailed description given below with reference to the accompanying drawings.